Top of McHugh's list: "It won't be a family drama, and it won't be set in a rural location." And lo! Her first full-length play, Helen and I, is exactly those things - a drama of two sisters returning to their father's deathbed in small-town Ireland.

You promise yourself things, says the 27-year-old, sitting in the Library Bar in Dublin city where she sipped a glass of sauvignon blanc after a rigorous first week in rehearsals. "But something else takes over when you're writing."

McHugh lives in Manhattan. Her achingly perfect placement there - living Off-Broadway on the Upper West Side, seeing "an abnormal amount of plays", doing a six-year PhD at Columbia where she counts Colm Tóibín as an "advisor" - makes you wonder where this intensely Irish, timeless play comes from. (Disclaimer: I've only read the script).

"I don't know where plays come from," she says. "But there's something great about growing up in a small town, for a writer. It's a little microcosm of the world, you have access to a whole spectrum of society, in a small place, and lots of different characters."

McHugh, oldest of three sisters, came of age in Tuam, Co Galway just like another Druid protégée, Tom Murphy - "a fantastic genius". She learnt to dance, act and sing at stage school and attended local amateur dramatics festivals.

In Druid-soaked Galway, she remembers coming out of the Town Hall Theatre in her late teens, weeping after The Walworth Farce.

Studying Drama and English at Trinity, she thought she would become an opera singer, but got nodules (like Adele) "and that kind of put an end to that". But, "I think there's some relationship between playwriting and singing. It's not just the words on the page, you're listening to the voices."

After college she acted in professional theatre, but "found out pretty quickly I didn't want to be an actor. I'm too inhibited! Acting, you get to explore other lives and other people, and other ideas and other voices. In writing, it's the same thing, you can try and be all these people but you do it in your room."

McHugh did so the summer she finished at The Lir. "I went home to Galway and locked myself in my room and wrote it."

"It" being Helen and I, the MA thesis turned debut full-length play. She sat for five weeks "looking on to a field" in her family's house in Corofin. "I remember that summer being difficult. I kept falling asleep, I had to take a lot of naps. You know that deep, subconscious work that drains you."

The characters of Helen and Lynn, says McHugh, "are complex and they're damaged. I'm interested in portraying women in their complexity, even if they're not the nicest women at times. You go through the motions of the characters. I've definitely been sitting there laughing at my own jokes and crying when there's something emotionally distressing happening. My mum and my sister got a lot of me coming into the kitchen and going, 'They've just said this! What do you think?'"

That was three sweet years ago. Druid gave Helen and I a rehearsed reading and now it has a dream team. Two fearsome leads, Rebecca O'Mara and Cathy Belton, the prestigious director Annabelle Comyn and Pan Pan's great stage designer, Aedin Cosgrove.

The play was going to be put on by Druid long before Waking the Feminists made female playwriting a political matter, Druid's artistic director Garry Hynes told me recently.

McHugh was "shocked" last winter when the Abbey released their man-packed programme for 2016. "I just feel lucky to come to the industry when things are shifting and opening, and there's more interest in other voices.

"Hopefully, there's going to be a more open and creative atmosphere for people of all different bodies and genders and races to put their stories forward. Otherwise, I dunno, you're just going to be putting on O'Casey forever! Even though he's great. I love the Irish canon, just, let's put on more - let's add on."

The play she is working on now is set neither in rural Ireland nor Columbia but in "an academic, artistic, Dublin world... This is wonderful that [Helen and I] is getting produced, but it was written three years ago."

McHugh may be doing sickeningly well for her 27 years, but the path wasn't all smooth. As an undergraduate she wrote a play about boys committing acts of violence in Galway and sent it away, to be rejected by both Druid and the Abbey. She laughs: "I already have my Abbey rejection letter, and I think that's good!"

Helen and I plays at the Mick Lally Theatre, Galway, September 9-18 and moves to the Civic, Tallaght, as part of Dublin Theatre Festival, September 27 to October 1